A $U$-Spin Anomaly in Charm CP Violation

Abstract

Recent LHCb data shows that the direct CP asymmetries of the decay modes $D^0\to {\pi }^{+}{\pi }^{-}$ and $D^0\to K^{+}{K}^{-}$ have the same sign, violating an improved $U$-spin limit sum rule in an unexpected way at $2.1\sigma$. From the new data, we determine for the first time the imaginary part of the CKM-subleading, $U$-spin breaking $\Delta U=1$ correction to the $U$-spin limit $\Delta U=0$ amplitude. The imaginary part of the $\Delta U=0$ amplitude is determined by $\Delta a_{CP}^{\mathrm{dir}}$. The corresponding strong phases are yet unknown and could be extracted in the future from time-dependent measurements. Assuming $\mathcal{O}(1)$ strong phases due to non-perturbative rescattering, we find the ratio of $U$-spin breaking to $U$-spin limit contributions to the CKM-subleading amplitudes to be $(173_{-74}^{+85})\%$. This highly exceeds the Standard Model (SM) expectation of $\sim 30\%$ $U$-spin breaking, with a significance of $1.95\sigma$. If this puzzle is confirmed with more data in the future, in the SM it would imply the breakdown of the $U$-spin expansion in CKM-subleading amplitudes of charm decays. The other solution are new physics models that generate an additional $\Delta U=1$ operator, leaving the $U$-spin power expansion intact. Examples for the latter option are an extended scalar sector or flavorful $Z^{\prime }$ models.

arXiv comment20 pages. Matches published version

References in corpus (44)

• FLAG Review 2021
• New Physics and CP Violation in Singly Cabibbo Suppressed D Decays
• New Strategies to Extract $\beta$ and $\gamma$ from $B_d\to {\pi }^{+}{\pi }^{-}$ and $B_s\to K^{+}{K}^{-}$
• Branching ratios and direct CP asymmetries in $D\to PP$ decays
• SU(3) Breaking and D0-D0bar Mixing
• Nonleptonic weak decays of charmed mesons
• Two-body hadronic charmed meson decays
• Size of direct CP violation in singly Cabibbo-suppressed D decays
• CP Violation and Flavor SU(3) Breaking in D-meson Decays
• A consistent picture for large penguins in D -> pi+ pi-, K+ K-
• Charm Meson Decays
• CP asymmetries in singly-Cabibbo-suppressed $D$ decays to two pseudoscalar mesons
• SU(3) Sum Rules for Charm Decay
• The Standard Model confronts CP violation in $D^0\to {\pi }^{+}{\pi }^{-}$ and $D^0\to K^{+}{K}^{-}$
• U-Spin Symmetry in Charmless B Decays
• SU(3)-Flavor Anatomy of Non-Leptonic Charm Decays
• Revisiting CP violation in $D\to PP$ and $VP$ decays
• Testing New Indirect CP Violation
• Topological amplitudes in $D$ decays to two pseudoscalars: a global analysis with linear $SU(3{)}_F$ breaking
• Repercussions of Flavour Symmetry Breaking on CP Violation in D-Meson Decays
• The Emergence of the $\Delta U=0$ Rule in Charm Physics
• Direct CP asymmetry in $D\to {\pi }^{-}{\pi }^{+}$ and $D\to K^{-}{K}^{+}$ in QCD-based approach
• The Role of $B_s\to K\pi$ in Determining the Weak Phase $\gamma$
• Testing for new physics in singly Cabibbo suppressed D decays
• New Physics Models of Direct CP Violation in Charm Decays
• On $SU(3{)}_F$ Breaking through Final State Interactions and CP Asymmetries in $D\to PP$ Decays
• $\Delta A_{CP}$ within the Standard Model and beyond
• Charmed meson decays to two pseudoscalars
• CP Violation in $D^0\to K_S{K}_S$
• Sum Rules of Charm CP Asymmetries beyond the SU(3)${}_F$ Limit
• CP violating asymmetries in charged D meson decays
• Implications of the LHCb discovery of CP violation in charm decays
• Exploiting CP-asymmetries in rare charm decays
• U-Spin Sum Rules for CP Asymmetries of Three-Body Charmed Baryon Decays
• Searching for the Origin of CP violation in Cabibbo Suppressed D-meson Decays
• Enhancement of charm CP violation due to nearby resonances
• $CP$ asymmetries in charm decays into neutral kaons
• Neutral $D\to K{K}^{\ast }$ decays as discovery channels for charm CP violation
• CP violation in D meson decays: would it be a sign of new physics ?
• More Flavor SU(3) Tests for New Physics in CP Violating B Decays
• General Analysis of U-Spin Breaking in B Decays
• Simple model for large CP violation in charm decays, B-physics anomalies, muon g-2, and Dark Matter
• Tasting Flavoured Majorana Dark Matter
• The Mathematical Structure of $U$-Spin Amplitude Sum Rules

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• Measurement of the time-integrated CP asymmetry in $D^0\to K_S^0{K}_S^0$ decays using Belle and Belle II data
• Implications of the evidence for direct $\mathbf{CP}$ violation in $D\to {\pi }^{+}{\pi }^{-}$ decays
• Measurement of the CP asymmetry in $D^{+}\to {\pi }^{+}{\pi }^0$ decays at Belle II
• Measurement of the time-integrated $CP$ asymmetry in $D^0\to K_{\mathrm{S}}^0{K}_{\mathrm{S}}^0$ decays using opposite-side flavor tagging at Belle and Belle II
• Measurement of $CP$ asymmetry in $D^0\to K_{\mathrm{S}}^0{K}_{\mathrm{S}}^0$ decays with Run 3 data
• Search for $CP$ violation in ${\Xi }_c^{+}\to {\Sigma }^{+}{h}^{+}{h}^{-}$ and ${\Lambda }_c^{+}\to p{h}^{+}{h}^{-}$ at Belle II
• Measurement of the time-integrated $CP$ asymmetry in $D^0\to {\pi }^0{\pi }^0$ decays at Belle II
• Search for $CP$ violation in $D_{(s)}^{+}\to K_S^0{K}^{-}{\pi }^{+}{\pi }^{+}$ decays using triple and quadruple products
• Polarisation fractions in $B\to V_1{V}_2$: U-Spin constraints and new physics signatures